一様流中の円柱周りの減圧挙動に対する微小慣性の影響(流体工学,流体機械)

抄録

Considering the flow around an object, the pressure averaged over its surface is less than the bulk one. In the present study, the depressurization behavior of a circular cylinder is theoretically and numerically investiated at the sufficiently small but non-zero Reynolds number. The dimensionless number "C_TDP", which is corresponding to the dimensionless depressurization scaled by the fluid density and the stream velocity, is used to organize the data. The method of matched asymptotic expansions is used to evaluate C_TDP expanded by "ε" (=log(8/Re)-γ+1/2)^-1). The theoretical result shows that the leading order term of C_TDP is ε² log Re and is affected by the outer field of the expansion. Direct Numerical Simulation (DNS) of a flow around the circular cylinder is carried out in order to verify the present theory. The C_TDP at the small Reynolds number (Re≤O(0.1)) obtained by the present theory shows good agreement with that by the DNS. On the other hand, the theoretical C_TDP at the higher Reynolds number (Re≥O(1)) remarkably deviates from the value obtained by the DNS because the assumption of the sufficiently small Reynolds number is no more justified.